Profile metadata
Both Mastodon and glitch-soc allow users to input optional key: value pairs in their bios, rendered in a table by the frontend and on static pages.
This is what it looks like for logged-in users on a glitch-soc server:

And for everyone else, it shows to the right of the avatar:

This is done from the profile edition page in glitch-soc’s settings.
Legacy glitch-soc implementation
Before being adopted upstream, glitch-soc users used optional key: value pairs as YAML-esque frontmatter at the beginning of their bios.
An example of a bio with this frontmatter is as follows:
---
Pronouns: any you like
Website: example.com
Whois: Unknown
Call me: Maybe
...
what's up
Syntax
In brief: start with
---, then addkey: valueone per line, and close it with...on it’s own line. Anything that follows is your bio text.
The syntax for profile frontmatter matches that used for single-line YAML implicit keys. Strings may be provided in single-quoted, double-quoted or plain (unquoted) styles.
Although glitch-soc borrows the syntax of YAML for its profile frontmatter, it does not borrow the semantics: Ordering and duplicate keys are preserved, and every value is interpreted as a string.
Links, hashtags, and mentions are all valid inside of frontmatter keys or values.